Catalytic composition for the oxidative ammonolysis of alkylpyridines

ABSTRACT

A new catalytic composition, comprising the oxides of vanadium, titanium, zirconium and molybdenum is disclosed. The new catalytic composition is applied in the oxidative ammonolysis of alkylpyridines.

This application is a 371 of PCT/EP95/01945 which is now published asWO95/32055 on Nov. 30, 1995.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to catalytic compositions, their use in theoxidative ammonolysis of alkylpyridines and to a process for theproduction of cyanopyridines.

Preferably the catalytic compositions are used for the oxidativeammonolysis of 3-methylpyridine and 2-methyl-5-ethylpyridine to thecorresponding 3-cyanopyridine.

3-Cyanopyridine is an intermediate for nicotinic acid or nicotinic acidamide which are essential vitamins of the B-complex.

2. Background Art

The oxidative ammonolysis of alkylpyridines is well known in the art. Agreat variety of catalyst systems have been disclosed but so far noprocess is known which can adequately satisfy the needs of a commercialprocess on a technical scale.

Reference is made to the USSR inventors certificate No. 891 142, whereina catalyst for the ammonolysis of alkylpyridines consisting of theoxides of vanadium, tin and titanium is described. The maximum yieldachieved for the conversion of for (e.g.) instance2-methyl-5-ethylpyridine is 63%. The main drawback of this catalyticcomposition therefore is its low activity and selectivity.

From Swiss patent 595 350, it is further known that 2-methyl-5-ethylpyridine can be converted to 3-cyanopyridine over a supported mixedoxide catalyst composed of oxides of vanadium, zirconium or titanium andoptionally of tungsten. The yields obtained with this catalyst rangebetween 60% and 75%. This catalyst is also not satisfactory due to itslow selectivity and activity. A further drawback is the rathercomplicated procedure for producing this supported catalyst.

BROAD DESCRIPTION OF THE INVENTION

The object of the present invention is to provide catalytic compositionswith further improved catalytic activity and performance and thereforeto provide an improved process for oxidative ammonolysis ofalkylpyridines especially with respect to selectivity and yield.

The catalytic composition of the present invention according to claim 1comprises the oxides of vanadium, zirconium, titanium and molybdenumhaving a molar ratio of V₂ O₅ to TiO₂ to ZrO₂ from 1:1:2 to 1:12:25 anda MoO₃ content of 0.54 to 2.6 weight percent relating to V₂ O₅.

A preferred catalytic composition has a molar ratio of V₂ O₅ to TiO₂ toZrO₂ from 1:3:4 to 1:8:16 and a MoO₃ content of 0.54 to 1.15 weightpercent relating to V₂ O₅. In order to prepare the catalytic compositionone can use the respective oxides itself but it is also possible to useprecursor compounds which are later converted into the oxides. Suchprecursor compounds are for example: vanadiumoxide, theammoniummetavanadate; zirconiumoxide, the zirconylchloride;titaniumoxide, the metatitaniumacid; and for the molybdenumoxide, theammoniummolybdate.

The preparation of the catalytic composition can as a rule beaccomplished by mixing the compounds in a suitable milling device,granulating or tabletting the mixture and finally drying the granules ortablets at a temperature of about 100° C. to 120° C. in a stream of air.The catalyst undergoes wiht advantage a subsequent thermal treatment attemperatures up to 650° C.

The ready prepared catalyst can then be charged into the reactor,wherein after an activation phase under reaction conditions, it is ableto demonstrate its properties with respect both to high activity andselectivity at high loadings of the alkylpyridine and also with respectto long service life.

The catalytic composition of the present invention is especiallysuitable for the oxidative ammonolysis of alkylpyridines in presence ofammonia, an oxygen containing gas and if necessary water vapour.Preferred application of the catalytic composition is the conversion of3-methylpyridine or 2-methyl-5-ethylpyridine to 3-cyanopyridine. Thefollowing process conditions have been proved to be suitable.

Air is generally used as the oxygen-containing gas. Thus air offers theadvantage that oxygen is already diluted with inert components. Thepartial pressure of oxygen can be advantageously regulated by furtherdilution with a suitable inert gas, for example nitrogen, or byrecycling part or most of the oxygen-lean exhaust gases.

Two advantages over the processes from the known state of the art isoffered in the conversion of 3-methylpyridine, which according to theinvention not only needs no addition of water vapour, but also uses apractically stoichiometric quantity or a small molar excess of ammonia.

The gaseous feed of the reactants in the case of the oxidativeammonolysis of 3-methylpyridine is accordingly composed of a molar ratioof3-methylpyridine to ammonia to air (calculated on the basis of oxygen)from 1:1:1.5 to 1:8.5:60.

A preferred gaseous feed is composed of a molar ratio of3-methylpyridine to ammonia to air (calculated on the basis of oxygen)from 1:1:2 to 1:4:60

The gaseous feed of the reactants in the case of the oxidativeammonolysis of 2-methyl-5-ethylpyridine is composed of a molar ratio of2-methyl-5-ethylpyridine to ammonia to air (calculated to O₂) and towater vapour from 1:20:20:60 to 1:60:70:330. The temperature in thereaction zone of the catalyst bed ranges expediently between 280° C. and400° C. and preferably between 310° C. and 380° C.

The characteristics of the catalytic composition also with respect tolife-time allow the process to be run continuously on a largescale-basis.

The maximum yield achieved with 3-cyanopyridine upon feeding up to 150 gper liter per hour of catalyst of 3-methylpyridine reaches 99%, and with2-methyl-5-ethylpyridine up to 120 g per liter per hour of catalystreaches 85%.

EXAMPLES Example 1

36.4 g of vanadiumpentoxide, 48.0 g of titaniumdioxide, 197.2 g ofzirconiumdioxide and 0.42 g of molybdenumtrioxide in the molar ratio V₂O₅ :TiO₂ :ZrO₂ =1:3:8 and 1.15 wt. % MoO₃ based on vanadiumpentoxide,were ground and mixed in a bail mill. The mixture was moulded intogranules of 5×5 mm and thermally treated at a temperature of 100°-120°C. for 6 hours in a flow of air. The obtained catalyst in the quantityof 60 cm³ (82 g) was loaded into a tube reactor made of stainless steel(internal diameter 20 mm, length 1000 mm). A mixture of the reagents,consisting of 2-methyl-5-ethylpyridine, air, ammonia, water vapour waspassed through the catalyst layer at a temperature of 340° C. Thefeeding rate (gram per 1 liter catalyst per 1 hour=gl⁻¹ h⁻¹) was:2-methyl-5-ethylpyridine--72 gl⁻¹ h⁻¹, air--1500 liters, ammonia--228gl⁻¹ h⁻¹ and water--583.3 gl⁻¹ h⁻¹ corresponding to a molar ratio of2-methyl-5-ethylpyridine to oxygen to ammonia to water of 1:47:45:108.Accordingly 21.6 g of 2-methyl-5-ethylpyridine was fed over 10 hours.The conversion was complete. 15.0 g of 3-cyanopyridine was obtainedcorresponding to a yield of 80.5% from theory. The output of3-cyanopyridine was 49.8 gl⁻¹ h⁻¹.

Example 2

A catalyst as described in example 1 was used. A mixture consisting of3-methylpyridine, air and ammonia was passed through the catalyst at atemperature of 330° C. The feeding rate (gram per 1 liter catalyst per 1hour=gl⁻¹ h⁻¹) was: 3-methylpyridine--84 gl⁻¹ h⁻¹, air-2000 liters,ammonia--9.92 gl⁻¹ h⁻¹ corresponding to a molar ratio of3-methylpyridine:O₂ :NH₃ =1:40:1.3. Accordingly 25.5 g of3-methylpyridine was fed over 10 hours. The conversion was complete.26.8 g of 3-cyanopyridine was obtained corresponding to a yield of 95.0%mol from theory. The output of 3-cyanopyridine was 89.2 gl⁻¹ h⁻¹.

Example 3

A catalyst was prepared from 36.4 g of vanadiumpentoxide, 64.0 g oftitanium dioxide, 98.6 g of zirconium dioxide and 0.2 g of MoO₃ in themolar ratio V₂ O₅ :TiO₂ :ZrO₂ =1:4:4 and 0.54% wt. % MoO₃ based on V₂O₅.

The catalyst was prepared by the method described in the example 1. Thegaseous feed consisting of 2-methyl-5-ethylpyridine air, ammonia andwater vapour was passed through the catalyst bed (60 cm³) at atemperature of 320° C. The feeding rate (gram per 1 liter catalyst per 1hour=gl⁻¹ h⁻¹) was: 2-methyl-5-ethylpyridine--72 gl⁻¹ h⁻¹, air--1500liters, ammonia--228 gl⁻¹ h⁻¹, water 700 gl⁻¹ h⁻¹ corresponding to amolar ratio of 2-methyl-5-ethylpyridine:O₂ :NH₃ :H₂ O of 1:47:45:130.Accordingly 21.6 g of 2-methyl-5-ethylpyridine was fed over 10 hours.The conversion was complete. 15.3 g 3-cyanopyridine was obtainedcorresponding to a yield of 82.2% based on the feed of2-methyl-5-ethylpyridine. The output of 3-cyanopyridine was 50.8 gl⁻¹h⁻¹.

Example 4

A catalyst with a molar ratio of V₂ O₅ :TiO₂ :ZrO₂ =1:4:4 and 0.90 wt. %of MoO₃ based on V₂ O₅ was prepared according to example 1. A mixtureconsisting of 3-methylpyridine, air, ammonia was passed through thecatalyst at a temperature of 330° C. The feeding rate (gram per 1 litercatalyst per 1 hour=gl⁻¹ h⁻¹) was: 3-methylpyridine--84 gl⁻¹ h⁻¹,air--2000 liters, ammonia--9.92 gl⁻¹ h⁻¹ corresponding to a molar ratioof 3-methylpyridine:O₂ :NH₃ of 1:40:1.3. Accordingly 25.2 g of3-methylpyridine was fed over 10 hours. The conversion was complete.27.3 g 3-cyanopyridine was obtained corresponding to a yield of 97.9%from theory. The output of 3-cyanopyridine was 91.0 gl⁻¹ h⁻¹.

Example 5

A catalyst with a molar ratio of V₂ O₅ :TiO₂ :ZrO₂ =1:4:8 and 0.98 wt. %of MoO₃ based on V₂ O₅ was prepared according to example 1. A mixtureconsisting of 2-methyl-5-ethylpyridine, air, ammonia and water vapourwas passed through the catalyst at a temperature of 320° C. The feedingrate (gram per 1 liter catalyst per 1 hour=gl⁻¹ h⁻¹) was:2-methyl-5-ethylpyridine--72 gl⁻¹ h⁻¹, air--1500 liters, ammonia--228gl⁻¹ h⁻¹ and water--700 gl⁻¹ h⁻¹ corresponding to a molar ratio of2-methyl-5-ethylpyridine:O₂ :NH₃ :H₂ O of 1:47:45:130. Accordingly 21.6g of 2-methyl-5-ethylpyridine was fed over 10 hours. The conversion wascomplete. 15.4 g of 3-cyanopyridine was obtained corrresponding to ayield of 83% based on the feed of 2-methyl-5-ethylpyridine. The outputof 3-cyanopyridine was 513 gl⁻¹ h⁻¹.

Example 6

A catalyst with a molar ratio V₂ O₅ :TiO₂ :ZrO₂ =1:4:8 and 1.15 wt % ofMoO₃ based on V₂ O₅ was prepared according to example 1. A mixtureconsisting of 3-methylpyridine, air, ammonia was passed through thecatalyst at a temperature of 325° C. The feeding rate (gram per 1 litercatalyst per 1 hour=gl⁻¹ h⁻¹) was: 3-methylpyridine--168 gl⁻¹ h⁻¹,air--2000 liters, ammonia--22.8 gl⁻¹ h⁻¹ corresponding to a ratio of3-methylpyridine:O₂ :NH₃ of 1:40:1.5. Accordingly 50.4 g of3-methylpyridine was fed over 10 hours. The conversion was complete.55.8 g of 3-cyanopyridine was obtained corresponding to a yield of 99.0%from theory. The output of 3-cyanopyridine was 186 gl⁻¹ h⁻¹.

Example 7

A catalyst with the molar ratio V₂ O₅ :TiO₂ :ZrO₂ =1:4:8 and 1.15 wt %of MoO₃ based on V₂ O₅ was prepared according to example 1. A mixtureconsisting of 3-methylpyridine, air, ammonia was passed through thecatalyst at a temperature of 350° C. The feeding rate (gram per 1 litercatalyst per 1 hour=gl⁻¹ h⁻¹) was 3-methylpyridine--218 gl⁻¹ h⁻¹,air--2000 liters, ammonia--30.35 gl⁻¹ h⁻¹ corresponding to a molar ratioof 3-methylpyridine:O₂ :NH₃ of 1:16:1.5. Accordingly 65.5 g of3-methylpyridine was fed over 10 hours. The conversion was complete.75.2 g of 3-cyanopyridine was obtained corresponding to a yield of 99.0%from theory. The output of 3-cyanopyridine was 241.7 gl⁻¹ h⁻¹.

Example 8

1.167 kg of vanadiumpentoxide, 2.512 kg of titaniumdioxide asmetatitanic acid, 6.322 kg of zirconiumdioxide and 12.4 g ofammoniumparamolybdate (molybdic acid) in the molar ratio V₂ O₅ :TiO₂:ZrO₂ =1:4:8 and 1.05% (NH₄)₆ Mo₇ O₂₄.4H₂ O based on vanadiumpentoxide,were kneaded in a double-am kneader and ground and mixed in a ball mill.The mixture was formed into granules of approximately 3×3 mm andthermally treated at a temperature of 100°-120° C. for 6 hours. Aquantity of the obtained catalyst (1 liter, 1.50 kg) was loaded into atube reactor made of stainless steel (internal diameter 21 mm, length 3meters). A mixture of reagents, consisting of 3-methylpyridine, air,nitrogen and ammonia, was passed through the catalyst at a temperatureof 340° C. The feeding rate (gram per 1 liter catalyst per hour=gl⁻¹h⁻¹) was: 3-methylpyridine 80 gl.sup.⁻¹ h⁻¹, air 200 liter.h⁻¹, nitrogen1200 liter.h⁻¹, ammonia 37.5 gl⁻¹ h⁻¹ corresponding to a molar ratio of3-methylpyridine to ammonia to oxygen of 1:2.6:2.2. Accordingly 1920 g3-methylpyridine was fed over 24 hours. The conversion was 99%. 1910 gof 3-cyanopyridine were obtained corresponding to a yield of 89%. Theoutput of3-cyanopyridine was 79.6 gl⁻¹ h⁻¹

Example 9

A quantity of the obtained catalyst from example 8 (985 cm³, 1.46 kg)was loaded into a tube reactor made of stainless steel (internaldiameter 21 mm, length 3 meters). A mixture of reagents, consisting of3-methylpyridine, air, recycled exhaust gas and ammonia, was passedthrough the catalyst at a temperature of 345° C. The feeding rate (gramper 1 liter catalyst per hour=gl⁻¹ h⁻¹) was: 3-methylpyridine 80 gl⁻¹h⁻¹, air 180 liter.h⁻¹, recycled exhaust gas 1200 liter.h⁻¹, ammonia52.5 gl⁻¹ h⁻¹ corresponding to a molar ratio of 3-methylpyridine toammonia to oxygen of 1:3.6:2.0. Accordingly 1890 g 3-methylpyridine wasfed over 24 hours. The conversion was 98.5%. 1850 g of 3-cyanopyridinewere obtained corresponding to a yield of 88.5%. The output of3-cyanopyridine was 77 gl⁻¹ h⁻¹.

Example 10

A quantity of the obtained catalyst from example 8 (135 cm³, 160 g) wasthermally treated at 620° C. for 6 hours. This was loaded into a tubereactor made of stainless steel (internal diameter 21 mm, length 1000mm). A mixture of reagents, consisting of 3-methylpyridine, air,nitrogen and ammonia, was passed through the catalyst at a temperatureof 375° C. The feeding rate was: 3-methylpyridine 11 gh⁻¹ (81 gl⁻¹ h⁻¹=gram per 1 liter catalyst per hour), air 30 liter.h⁻¹, nitrogen 285liter.h⁻¹, ammonia 4 gh⁻¹ corresponding to a molar ratio of3-methylpyridine to ammonia to oxygen of 1:2:2.6. Accordingly 264 g3-methylpyridine was fed over 24 hours. The conversion was 99%. 261 g of3-cyanopyridine were obtained corresponding to a yield of 89%. Theoutput of 3-cyanopyridine was 80 gl⁻¹ h⁻¹.

                                      TABLE I                                     __________________________________________________________________________    Oxidative ammonolysis of 2-methyl-5-ethylpyridine (MEP)                       ratio of the catalyst components                                                           in wt. %                     3-cyanopyridine                                  relating            Temper-                                                                            Conver-                                                                           molar                                                                             output                          in mol       to V.sub.2 O.sub.5                                                                 feed g/l of cat. per hour                                                                    ature,                                                                             sion,                                                                             yield,                                                                            g/l of                          example                                                                           V.sub.2 O.sub.5                                                                  TiO.sub.2                                                                        ZrO.sub.2                                                                        MoO.sub.3                                                                          MEP                                                                              air                                                                              ammonia                                                                            water                                                                             °C.                                                                         %   %   cat./h                          __________________________________________________________________________    11  1  4  10 1.15 72 1500                                                                             228  583.3                                                                             320  100 80.7                                                                              50.0                            12  1  4  12 0.54 72 1500                                                                             228  700 320  100 79.0                                                                              48.9                            13  1  5  16 0.90 76 1500                                                                             228  700 320  100 78.5                                                                              51.7                            14  1  3  8  0.90 126.6                                                                            1500                                                                             228  1000                                                                              340  100 78.5                                                                              85.2                            15  1  4  8  0.90 134.7                                                                            1500                                                                             228  1000                                                                              360  100 78.0                                                                              90.0                            16  1  1  6  1.15 72 1500                                                                             228  700 320  100 62.0                                                                              42.5                            17  1  4  18 0.90 72 1500                                                                             228  700 320  100 74.0                                                                              50.8                            18  1  6  2  0.54 72 1500                                                                             228  700 340  100 67.0                                                                              46.0                            __________________________________________________________________________

                                      Table II                                    __________________________________________________________________________    Oxidative ammonolysis of 3-methylpyridine (3-Pic)                             ratio of the catalyst components                                                           in wt. %                 3-cyanopyridine                                      relating        Temper-                                                                            Conver-                                                                           molar                                                                             output                              in mol       to V.sub.2 O.sub.5                                                                 feed g/l of cat. per hour                                                                ature,                                                                             sion,                                                                             yield,                                                                            g/l of                              example                                                                           V.sub.2 O.sub.5                                                                  TiO.sub.2                                                                        ZrO.sub.2                                                                        MoO.sub.3                                                                          3-Pic                                                                            air                                                                              ammonia                                                                            °C.                                                                         %   %   cat./h                              __________________________________________________________________________    19  1  10 8  0.90 84 2000                                                                             11.4 325  100 82.0                                                                              77.0                                20  1  6  2  0.54 84 2000                                                                             11.4 330  100 90.0                                                                              84.6                                21  1  4  10 1.15 84 2000                                                                             11.4 330  100 94.0                                                                              88.4                                22  1  4  12 0.54 84 2000                                                                             11.4 325  100 95.0                                                                              89.3                                23  1  5  16 0.90 84 2000                                                                             11.4 330  100 92.5                                                                              86.6                                24  1  4  8  0.90 126                                                                              2000                                                                             17.1 330  100 99.2                                                                              139.9                               25  1  4  8  0.90 136                                                                              2000                                                                             19.7 3501 100 99.0                                                                              151.3                               __________________________________________________________________________

We claim:
 1. Catalytic composition consisting of the oxides of vanadium,titanium, zirconium and molybdenum having a molar ratio of V₂ O₅ to TiO₂to ZrO₂ of from 1:1:2 to 1:12:25 and having a MoO₃ content of 0.54 to2.6 weight percent, relating to V₂ O₅.
 2. Catalytic composition asclaimed in claim 1 having a molar ratio of V₂ O₅ to TiO₂ to ZrO₂ of from1:3:4 to 1:8:16 and having a MoO₃ content of 0.54 to 1.15 weightpercent, relating to V₂ O₅.
 3. Process comprising using the catalyticcomposition of claim 1 for the oxidative ammonolysis of analkylpyridine.
 4. Process according to claim 3 wherein said catalyticcomposition is used for the oxidative ammonolysis of 3-methylpyridine or2-methyl-5-ethylpyridine.
 5. Process for the preparation of acyanopyridine by oxidative ammonolysis of an alkylpyridine, comprisingpassing the alkylpyridine together with ammonia, an oxygen-containinggas and, if necessary, water vapor over the catalytic composition asclaimed in claim 1 at a temperature of from 280° C. to 400° C. 6.Process according to claim 5 for the preparation of 3-cyanopyridine byoxidative ammonolysis of 3-methylpyridine, comprising passing the3-methylpyridine, ammonia and an oxygen-containing gas, calculated toO₂, in a molar ratio of from 1:1:1.5 to 1:8.5:60 over said catalyticcomposition at a temperature of from 310° C. to 380° C.
 7. Processaccording to claim 6 wherein the molar ratio of 3-methylpyridine toammonia to oxygen-containing gas is 1:1:2 to 1:4:60.
 8. Processaccording to claim 5 for the preparation of 3-cyanopyridine by oxidativeammonolysis of 2-methyl-5-ethylpyridine, wherein the2-methyl-5-ethylpyridine, ammonia, an oxygen-containing gas, calculatedto O₂, and water vapor in a molar ratio of from 1:20:20:60 to1:60:70:330 is passed over said catalytic composition at a temperatureof from 310° C. to 380° C.
 9. Process comprising using the catalyticcomposition of claim 2 for the oxidative ammonolysis of analkylpyridine.
 10. Process according to claim 9 wherein said catalyticcomposition is used for the oxidative ammonolysis of 3-methylpyridine or2-methyl-5-ethylpyridine.
 11. Process for the preparation of acyanopyridine by oxidative ammonolysis of an alkylpyridine comprisingpassing the alkylpyridine together with ammonia, an oxygen-containinggas and, if necessary, water vapor over the catalytic composition asclaimed in claim 2 at a temperature of from 280° C. to 400° C. 12.Process according to claim 11 for the preparation of 3-cyanopyridine byoxidative ammonolysis of 3-methylpyridine, comprising passing the3-methylpyridine, ammonia and an oxygen-containing gas, calculated toO₂, in a molar ratio of from 1:1:1.5 to 1:8.5:60 over said catalyticcomposition at a temperature of from 310° C. to 380° C.
 13. Processaccording to claim 12 wherein the molar ratio of 3-methylpyridine toammonia to oxygen-containing gas is 1:1:2 to 1:4:60.
 14. Processaccording to claim 11 for the preparation of 3-cyanopyridine byoxidative ammonolysis of 2-methyl-5-ethylpyridine, wherein the2-methyl-5-ethylpyridine, ammonia, an oxygen-containing gas, calculatedto O₂, and water vapor in a molar ratio of from 1:20:20:60 to1:60:70:330 is passed over said catalytic composition at a temperatureof from 310° C. to 380° C.